Balance wheel and hairspring holder



May 10, 1955 w v, BOLTON 2,707,890

BALANCE WHEEL AND HAIRSPRING HOLDER Filed Jan. 29, 1953 Wilbert V. Ba/fan INVENTOR.

United States Patent BALANCE WHEEL AND HAIRSPRING HOLDER Wilbert V. Bolton, King City, Calif.

Application January 29, 1953, Serial No. 334,048

3 Claims. (Cl. 81-6) This invention relates to work holders and more particularly to a holder for balance wheel and hair spring assemblies which enable the repairman to inspect and perform truing operations on a hair spring to great advantage.

An object of this invention is to provide a work hair spring is not distorted by the effect of centrifugal force, such as is common when spun in existing truing calipers.

Another object is to provide a device which allows a full and unobstructed view of the hair spring both in the fiat and in the round.

Still another object is to provide a device whereby it is possible to determine the exact place of distortion in a hair spring without removing it from the balance wheel, thus eliminating the procedure of removing the hair spring and truing it separately on a brooch.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawing forming a part hereof, wherein like numerals refer to like parts throughout and in which:

Figure 1 is a perspective view of the device operatively supporting a balance wheel and hair spring assembly;

Figure 2 is a vertical section taken substantially along line 2-2 of Figure 1 and showing details of construction of the device on an enlarged scale; and

Figure 3 is a vertical section taken substantially along line 3--3 of Figure 2 and showing the relationship between various parts of the device and the supported balance wheel and hair spring assembly.

Referring now more particularly to the drawings, reference numeral indicates generally a substantially flat or plate-like base which may conveniently take the form of a flat plate having a cut-away portion. As shown, the base consists of a lower horizontal portion 12 having an upper vertical portion 14 joined thereto to define generally an L-shaped member. Upper edge 16 of base portion 12 has an inverted L-shaped post 18 mounted thereon and the upper free end 20 of this post extends substantially parallel to edge 16 and terminates in a pivot bearing 22. The upper end of vertical base portion 14 is formed as a journal block 24 having a longitudinal bore 26 therein extending generally parallel to edge 16 and whose axis is co-linear or in register with the free end 20 of post 18.

A spindle 28 is journaled within the bore 26 and projects outwardly beyond the opposite sides of vertical base por- 2,707,890 Patented May 10, 1955 tion 14 and is provided at one end with a handle 30 which may be manipulated by an operator of the devices as will presently appear. The other end of the spindle is provided with a portion of reduced diameter presenting a nose 32 which terminates in a pivot bearing 34. It will be understood that the two pivot bearings 22 and 34 are disposed in opposed coaxial relationship so as to pivotally support the staff 35 of a balance wheel.

Frictionally engaged upon the main body portion of the spindle 8 adjacent nose 32 is a split collet 36 having a shoulder portion 38 constituting a spring seat. In order to urge nose 32 in a direction toward post 18, a spring 40 is disposed concentrically of spindle 28 and abuts against shoulder 38 and a thrust washer 42 positioned between one end of the spring 40 and the journal block 24. The spring 40 is constructed of such weight as to provide proper alignment between the balance wheel staff 35 and the pivot bearings 22 and 34 and yet the spring must be sutficiently light to prevent damage to the balance wheel staff. In this respect, it will be understood that it is preferable to form the post 18 of sufilciently light weight so that the same may be deflected should the spindle be jarred or forced inwardly toward the post when a balance wheel assembly is operatively engaged in the device, thus preventing damage to the balance wheel staff.

End 44 of collet 36 is spaced from thrust washer 42 when a balance wheel assembly is supported in the device, this being necessary to allow sliding of the spindle 28 within bore 26 when it is desired to remove the balance wheel assembly from the pivot bearings.

Collet shoulder 38 carries a resilient finger 46 which comprises a radially extending portion 48 secured to the shoulder and a horizontal portion 50 which extends in spaced parallel relation to the axis of spindle 38 toward post 18. This finger frictionally engages lightly upon the rim 52 of the balance wheel.

The balance wheel carries, in the conventional manner, a spiral hair spring 54 which is secured at its free end to the usual securing roller 56. Although the simplest form of hair spring is herein shown, it will be understood that other conventional types of hair springs may be trued with equal advantage in the holder.

In operation, a balance wheel and hair spring assembly is inserted in the holder by grasping spindle handle 30 and sliding the spindle in bore 26 to a position wherein the pivot bearings 22 and 34 are sutficiently spaced apart to allow the insertion of balance wheel staff 35 therebetween. Thereupon, spindle 28 is allowed to slide toward post 18 under the action of spring 40 whereby the balance wheel staff 35 will be securely supported between the pivot bearings and resilient finger 46 will be lightly but frictionally engaged upon the rim of the balance wheel. Since collet 36 is frictionally engaged upon spindle 28 and resilient finger 46 is secured to the collet and frictionally engages the rim of the balance wheel, a watch maker or repairman upon rotating spindle 28 slowly may have free and unobstructed view of the hair spring both in the flat and in the round. In this manner, it can readily be determined whether the hair spring is distorted in such a manner that the coils are not coplanar, whether or not the plane of the hair spring is parallel to the plane of the balance wheel, or whether the spiral concentricity of the hair spring is distorted at any point. Therefore, should any of these conditions exist, they will be readily apparent and may be easily and quickly corrected.

If it be desired, the base 10 can be inserted in a vise or other suitable holder or the lower end of the base may be provided with a standard for supporting the device on a fiat surface.

The spindle, being at all times under control of the user, can be rotated in any desired speed or to any posi- 3 tion desired so as to enable the hair spring to be inspected and trued in a most efficient manner.

From the foregoing, the construction and operation of the device will be readily understood and further explanation is believed to be unnecessary. However, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the appended claims.

What is claimed as new is as follows:

1. A balance wheel and hair spring holder comprising an L-shaped base presenting a horizontal portion and a vertical portion, an inverted L-shaped post secured at its lower end to said horizontal portion and having its upper end extending toward said vertical portion and terminating in a first pivot bearing, a spindle slidably and rotatably journalled in said vertical portion and having one end presenting a second pivot bearing in opposed relation to the first bearing, a split sleeve frictionally engaged on said one end of the spindle, said sleeve having a radial shoulder, and a spring disposed between said base and said shoulder for urging the spindle toward the post.

2. A balance wheel and hair spring holder comprising an L-shaped base presenting a horizontal portion and a vertical portion, an inverted L-shaped post secured at its lower end to said horizontal portion and having its upper end extending toward said vertical portion and terminating in a first pivot bearing, a spindle slidably and rotatably journalled in said vertical portion and 3 having one end presenting a second pivot bearing in opposed relation to the first bearing, a split sleeve frictionally engaged on said one end of the spindle, said sleeve having a radial shoulder, and a spring disposed between said base and said shoulder for urging the spindle toward the post, a finger on said sleeve extending in spaced parallel relation to said spindle toward said post, said finger being adapted to engage the rim of a supported balance wheel.

3. A balance wheel and hairspring holder comprising a base having first and second spaced portions, a first pivot bearing carried by said first portion, a spindle slidably and rotatably journaled in said second portion, one end portion of said spindle projecting beyond said second portion and terminating in a second pivot bearing in opposed relation to said first pivot bearing, a spring seat carried by said one end portion of said spindle, a spring disposed between said seat and said second portion for urging said second pivot bearing toward said first pivot bearing, and a finger carried by said spring seat and extending toward said first portion for engaging the rim of a supported balance wheel.

References Cited in the file of this patent UNlTED STATES PATENTS 982,635 Rogers et al Jan. 24, 1911 2,106,653 Podgurski Jan. 25, 1938 2,429,139 Scard'accionc Oct. 14, 1947 FOREIGN PATENTS 33,107 Switzerland Mar. 24, 1905 

